The RFID tag in your passport knows who and where you are.

This says "proposed"...Regarding existing Passports from the article.The approach is substantially different from the proximity-read technology being used in U.S. electronic passports, and it offers fewer protections, according to Ari Schwartz, deputy director at the CDT. Electronic passports contain all of the same identification data that appears on the first page of a passport, and includes a digital photograph and a digital signature. But the information on those chips is encrypted at all times and can only be accessed by physically swiping the card through a reader at the border crossing.